It is poor style for test cases to use the internal API (i.e.
libzmq classes or header files), as this code serves the purpose
of teaching developers how to use the library (it doesn't do this
very well, it's an ambition).

Also, including headers in src/ creates problems when compiling.

Solution: remove use of src/macros.hpp.

This commit addresses the following warnings reported on gcc 5.2.1. In
the future, this will help reduce the "noise" and help catch warnings
revealing a serious problem.

8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---
/path/to/libzmq/src/options.cpp:1048:36: warning: unused parameter ‘option_’ [-Wunused-parameter]
 bool zmq::options_t::is_valid (int option_) const
                                    ^

/path/to/libzmq/src/plain_client.cpp:146:30: warning: unused parameter ‘cmd_data’ [-Wunused-parameter]
         const unsigned char *cmd_data, size_t data_size)
                              ^

/path/to/libzmq/src/plain_client.cpp:146:30: warning: unused parameter ‘cmd_data’ [-Wunused-parameter]
         const unsigned char *cmd_data, size_t data_size)
                              ^

/path/to/libzmq/src/socket_base.cpp:1445:44: warning: unused parameter ‘group_’ [-Wunused-parameter]
 int zmq::socket_base_t::xjoin (const char *group_)
                                            ^
/path/to/libzmq/src/socket_base.cpp:1451:45: warning: unused parameter ‘group_’ [-Wunused-parameter]
 int zmq::socket_base_t::xleave (const char *group_)
                                             ^

/path/to/libzmq/src/radio.cpp:145:33: warning: unused parameter ‘msg_’ [-Wunused-parameter]
 int zmq::radio_t::xrecv (msg_t *msg_)
                                 ^
/path/to/libzmq/src/dish.cpp:164:32: warning: unused parameter ‘msg_’ [-Wunused-parameter]
 int zmq::dish_t::xsend (msg_t *msg_)
                                ^

/path/to/libzmq/tests/test_msg_ffn.cpp:32:16: warning: unused parameter ‘data’ [-Wunused-parameter]
 void ffn(void *data, void *hint) {
                ^

/path/to/libzmq/tests/test_timers.cpp:50:19: warning: unused parameter ‘timer_id’ [-Wunused-parameter]
 void handler (int timer_id, void* arg)
                   ^
8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---8<---

Solution: update to 2016

new allocation caused reference counters to lose track on copy